The invention pertains to fire extinguishing systems in buildings, and more particularly, to systems for treating the water in these fire extinguishing systems with chemicals.
The treatment of water systems is known in the art, such as those disclosed in U.S. Pat. Nos. 4,460,008 (O""Leary et al.); 4,464,315 (O""Leary); 4,648,043 (O""Leary); 4,659,459 (O""Leary et al.).
However, with particular regard to the fire sprinkler industry, the latter has not considered the application of chemicals to treat the water within fire sprinkler systems because of complications in their design that makes normal treatment methods useless and ineffective. Recent failures of fire sprinkler systems due to corrosion and bacteria attack are showing up at an alarming rate causing damage and loss of life. These failures are causing product recalls and in some cases, systems are being turned off because of the high cost of replacement.
The design of a fire sprinkler system consists of an upright pipe 10 (FIG. 2) called a riser that draws water from the city water pipe, tank, pond or river (see reference number 12 in FIG. 2). The risers 10 normally are 6 or 8 inch diameter pipe having a shutoff valve 14, main drain valve 16, flow alarm valve, and pressure detector. The purpose of the riser 10 is to carry water to the ceiling where it enters a header pipe 11 that carries water along the ceiling to lateral pipes 13, which come off the header pipe about every 10 to 20 feet. The lateral pipe has sprinkler heads attached to the top or bottom of the lateral about every 10 to 20 feet. The furthermost lateral pipe 15 has a 1xe2x80x3 pipe extending down the wall and exiting through the wall to the outside, where water can be dumped for testing purposes. This line has a valve attached, which is known as the xe2x80x9cInspector""s Test Valvexe2x80x9d 18. The purpose of this valve 18 and line is to test the alarm valve on the riser 10, which should alarm when approximately 30 gallons of water are dumped causing flow and pressure drop. This test represents what would happen if one sprinkler was activated.
The piping design of fire sprinkler systems is unique and different from design parameters of all other water piping. The first sprinkler design is a xe2x80x9cdead-endedxe2x80x9d pipe system. That is, once the system is filled, the water will not be changed until a fire activates a sprinkler allowing flow to occur. As a result, fire sprinkler systems are considered xe2x80x9cclosed water systems.xe2x80x9d In fact, many of these systems include a back flow preventor such that once water is inputted into the sprinkler system, it cannot reverse.
Once or up to four times a year the inspector""s valve is tested allowing only thirty gallons of water to flow. The average riser system contains 1500 to 2000 gallons of water. Most building have several riser systems each covering about 40,000 square feet apiece. This design allows corrosion to occur and not be detected. That is, almost the entire internal cross sectional area can be plugged with corrosion byproducts and still allow 30 gallons per minute to flow. Only when a fire occurs will the plugged pipe be detected. That is the system cannot allow sufficient water to flow to put out the fire. The corrosion byproducts can also plug the sprinkler heads causing failure.
One knowledgeable in the application of chemicals into water systems would easily see the futility of trying to feed and control chemicals in a 6 inch or 8 inch diameter riser pipe flowing at its rated capacity. A chemical feed pump does not exist that would handle this flow rate. As the dead-ended system starts filling, the pressure would start building and this would cause a reduction in flow. This would cause even greater chemical feed and control problems. Further complications will develop because of laminar flows within the pipes. These flow would not allow uniform mixing of chemicals within the pipe. Pipe design will not allow in-line mixers because of restricted water flows. Improper chemical concentrations would develop causing greater under deposit corrosion from precipitated chemicals. This same conditions would occur if one were to throttle the riser shut off valve 14. Adding to the complication of feeding and mixing is the compatibility of a chemical biocide with a corrosion inhibitor. These cannot be fed in a concentrated form together. They must be diluted in water first to prevent reactions and to be effective.
U.S. Pat. No. 5,803,180 (Talley) discloses a method whereby a buffering compound (e.g., sodium hydroxide) is injected into a fire sprinkler system water to maintain the pH of the water in a range of 9.5-11. The patent also suggests the use of a dielectric coupling at the sprinkler head/iron service tee connections of the fire sprinkler system.
In view of all of the above, there remains a need for a portable system and method of treating the water in a fire sprinkler system.
A fire sprinkler treatment apparatus is provided for automatically treating the water of a fire sprinkler system with at least one chemical (e.g., bromine, or biocide and corrosion inhibitor). The apparatus is adapted to be coupled between the fire sprinkler system and a water source (e.g., city water line, fire hydrant, ) that supplies the fire sprinkler system with water. The apparatus comprises a portable frame that permits the apparatus to be transported.
A method for automatically treating the water of a fire sprinkler system with at least one chemical (e.g., bromine, or biocide and corrosion inhibitor) is provided and wherein the fire sprinkler system comprises a main riser and a water source for supplying water to the fire sprinkler system. The method comprises the steps of: (a) isolating the main riser from the water source and emptying the main riser of the existing water therein; (b) providing a supply of the at least one chemical; (c) determining a conductivity setpoint at which the at least one chemical is effective; (d) coupling a delivery means of the at least one chemical between the main riser of the fire sprinkler system and the water source so that a flow of water is created from the water supply to the main riser; (e) delivering-the at least one chemical from the supply to the flow of water towards a mixing chamber where the at least one chemical is mixed; (f) monitoring the conductivity of the water flow out of the mixing chamber that is delivered to the main riser; (g) comparing the monitored conductivity with the setpoint; (h) repeating steps e-g as long as the monitored conductivity is less than the setpoint.